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73 Cards in this Set
- Front
- Back
Magnetism |
Force by which materials exert an attraction or repulsion on other materials. |
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Magnet |
Substance that produces a magnetic field. |
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Magnetic field |
A force produced by a magnet that exerts a force on moving electric charges or on other magnets |
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Permanent Magnet |
A magnet that can hold its magnetism for a long time. |
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Temporary Magnet |
A magnet that retains trace amounts of magnetism after a magnetizing force has been removed. |
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Retentivity |
A measure of the ability of a magnet to retain magnetism after the magnetizing force has been removed. |
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Magnetic Flux |
Invisible lines of force that make up the total quantity of a magnetic field. |
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Flux density |
The amount of concentration of magnetic flux through a specific area. |
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Permeability |
Measure of the ability of a material to conduct magnetic flux. |
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Ferromagnetic Material |
A material that is easily magnetized and with a high permeability. |
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Electromagnet |
A temporary magnet produced when electricity passes through a conductor, such as a coil, that concentrates the magnetic field. |
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Electromagnetism |
The temporary magnetic field produced when electricity passes through a conductor. |
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Inductance |
The property of a device or circuit that causes it to store energy in an electromagnetic field. |
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Self-induction |
The ability of an inductor in a circuit to generate inductive reactance, which opposes change in the current. |
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Mutual Induction |
The ability of an inductor (coil) in one circuit to induce a voltage in another circuit or conductor. |
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Nameplate |
Metal tag permanently attached to an electric motor that gives the required electrical ratings, operating ratings, and mechanical-design codes |
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Motor voltage rating |
The voltage level that a motor can use. |
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Motor current rating |
The amount of current a motor draws when delivering full rated power output. |
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Frequency Rating |
The power line frequency at which a motor is designed to operate. |
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Motor Power Rating |
Amount of power a motor can deliver to a load. |
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Locked-rotor current (LRC) |
The amount of current a motor draws on startup or when rotor is locked. Also known as inrush current or starting current. |
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Locked- rotor Indicating Code Letter |
A designation for the range Of locked-rotor current draw per motor horsepower. |
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Motor Usage Rating |
A description of the expected or allowed application of a motor. |
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Service Factor Rating |
A multiplier that represents the amount of load, beyond the rated load, that can be placed on a motor without causing damage. |
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Motor Speed Rating |
The approximate speed at which the rotor of a motor rotates when delivering rated power to a load, |
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Slip |
The difference between the synchronous speed and operating speed. |
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Duty Cycle |
The amount of time a motor can be Operated without being turned Off for cooling. |
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Motor Efficiency |
A measure of the effectiveness with which a motor converts electrical energy to mechanical energy. |
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Ambient Temperature Rating |
The max allowable temperature of the air surrounding an object. |
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Temperature Rise |
The difference between the Winding Temperature of a running motor and the ambient temperature. |
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Permissable Temperature Rise |
The difference between the ambient temperature and the nameplate ambient temperature rating of a motor. |
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Insulation Class |
A code letter signifying the max Operating temperature Of the insulation used in a motor |
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Frame Size |
A number designating standard dimensions Of a motor housing, Shaft, and mounting holes, |
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NEMA Design Letter |
A code letter representing a NEMA motor classification for the torque and current curves Of a motor. |
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Enclosure Type |
The type of protection given to a Motor to Shield the motor from the outside environment as well as protect individuals from the electrical and rotating parts of the motor. |
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Open Motor Enclosure |
A motor enclosure with openings to allow passage of air to cool the windings |
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Totally Enclosed Motor Enclosure |
A motor Enclosure that prevents air from entering the motor |
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Motor Bearing |
A machine component used to reduce friction and maintain clearance between Stationary and moving parts. |
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Alternator |
A synchronous machine that produces alternating current(AC) |
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Stator |
The fixed unmoving part Of a generator, consisting of a core and Windings, that convert energy If a magnetic field to electrical energy |
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Rotor |
The rotating moving part of an alternator or generator, consisting of a core and windings, that convert torque to magnetic energy |
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Torque |
A turning or twisting force that causes an object to rotate. |
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Revolving-field Alternator |
An alternator Where a magnetic field is created in the rotor, which turns within the fixed stator windings, and AC power is supplied through the stator windings |
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Exciter Generator |
An assembly consisting of a small three-phase alternator used to supply Current to an alternator rotor |
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Brushless Exciter |
A rectifier assembly mounted on the main rotor shaft along with the exciter generator |
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Revolving-rotor Alternator |
An alternator where a fixed magnetic field is created in the stator, with the rotor turning within the Stator, and AC power is supplied through the rotor slip rings and brushes |
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Field Windings |
Are electromagnetic coils that provide the DC for the exciter |
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Prime Mover |
The power source used to create the relative motion between the Coil and the magnetic field |
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Synchroscope |
A device that indicates Whether two AC sources to be connected in parallel are in the Correct phase relationship |
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Rotors and Stators |
Are found in AC equipment |
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Field Frames and Armatures |
Are found in DC equipment |
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Alternators Produce |
AC power |
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Generators produce |
DC power |
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Shaded- pole Motor |
An AC motor that uses a shaded Stater pole for starting |
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Shaded Pole |
A short- circuited winding, consisting of a single turn of copper wire, that acts on only a portion of the stator windings |
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Shading Coil |
A single turn of copper wire wrapped around part of the salient pole of a shaded-pole motor |
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Split-phase Motor |
A single-phase AC motor that includes a run winding and a resistive start winding that creates a phase-shift for starting |
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Centrifugal Switch |
A switch that opens to disconnect the start winding When the rotor reaches a certain preset speed and reconnects the start winding When the speed falls below a preset value |
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Capacitor Motor |
A single- phase motor With a capacitor connected in series with the start windings to produce phase displacement in the start winding |
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Capacitor |
A device that stores an electric Charge |
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Full Voltage Starting |
A method of starting a motor with the full line voltage placed across the terminals. |
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Manual Contactor |
A control device that uses pushbuttons that are part of the contactor to energize or de energize the load connected to it |
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Manual starter |
A contactor with an added overload protection device. Manual starters are used in electrical motor starters. |
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Locked Rotor |
Either the large current at instant of startup when a motor is connected to the rated load or it is a condition when a motor is loaded so heavily that the motor shaft cannot turn |
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Magnetic Motor Starter |
An electrically operated switch that includes motor overload protection. |
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Primary-Resistor Starting |
A method of reduced voltage starting that place a resistor in series in the motor power circuit to reduce the voltage to the motor. |
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Part-Winding Starter |
A method of reduced voltage starting that applies a voltage to only part of the motor coil windings for starting and then applies power to the remaining coil windings for normal running. |
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Soild-State Starter |
A motor starter that uses a solid state device, such as an insulated gate bipolar transistor (IGBT) silicon controlled rectifier (SCR), to control motor voltage, current, torque, and speed during acceleration. |
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Soft Starter |
A device that provides a gradual voltage increase (ramp up) during AC motor starting. |
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Plugging |
A method of motor braking in which the motor connections are reversed so that a motor develops a countertorque that acts as a braking force. |
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Electric Braking |
A method of braking in which a DC voltage is applied to the stator windings of a motor after AC voltage is removed. Also know on as DC injection. |
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Dynamic Braking |
A method of motor braking where braking energy is dissipated as heat in a resistor as a motor is reconnected to act a s generator immediately after it is turned off. |
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Regenerative Braking |
A method of dynamic braking that reuses the braking energy to the AC source instead of dissipating the energy as heat. |